WordPress has a template system, which includes widgets  that can be rearranged without editing PHP or HTML code, as well as themes that can be installed and switched between. The PHP and HTML code in themes can also be edited for more advanced customizations. Word Press also features integrated link management; a search engine-friendly, clean permanent  structure; the ability to assign nested, multiple categories to articles; and support for tagging of posts and articles. Automatic filters that provide for proper formatting and styling of text in articles (for example, converting regular quotes to smart quotes) are also included. Word Press also supports the Track back and Ping back  standards for displaying links to other sites that have themselves linked to a post or article. Finally, Word Press has a rich plug-in architecture which allows users and developers to extend its functionality beyond the features that come as part of the base install.